I want to remove all special characters and spaces from a string and replace with an underscore. The string is var str = "hello world & hello universe"; I have this now which replaces only spaces: str.replace(/\s/g, "_"); The result I get is `hello_world_&_hello_universe`, but I would like to remove the special symbols as well. I tried this `str.replace(/[^a-zA-Z0-9]\s/g, "_")` but this does not help.